What cubic inch is too large?
Okay. So if your at turbine limit at a 370 wouldn't a bigger turbo work the same? That way the 370 could make more power and run more boost?
I am very curious on the subject because it seems like i should stay at my cubic in and get a more "efficient" setup to make more power to run more boost rather than go up in cubic inches
I am very curious on the subject because it seems like i should stay at my cubic in and get a more "efficient" setup to make more power to run more boost rather than go up in cubic inches
Launching!
Joined: Oct 2006
Posts: 201
Likes: 0
From: Grand Rapids, MI
I am confused as well.
If your at the turbine limit of the turbo (that's what I am assuming you mean) then getting a bigger turbine would be equally "efficient" as a 4.8/5.3 that's not at its turbine limit?
That probably made it more confusing. I'm not making statements I'm just trying to understand.
If your at the turbine limit of the turbo (that's what I am assuming you mean) then getting a bigger turbine would be equally "efficient" as a 4.8/5.3 that's not at its turbine limit?
That probably made it more confusing. I'm not making statements I'm just trying to understand.
Launching!
Joined: Oct 2006
Posts: 201
Likes: 0
From: Grand Rapids, MI
I am confused as well.
If your at the turbine limit of the turbo (that's what I am assuming you mean) then getting a bigger turbine would be equally "efficient" as a 4.8/5.3 that's not at its turbine limit?
That probably made it more confusing. I'm not making statements I'm just trying to understand.
If your at the turbine limit of the turbo (that's what I am assuming you mean) then getting a bigger turbine would be equally "efficient" as a 4.8/5.3 that's not at its turbine limit?
That probably made it more confusing. I'm not making statements I'm just trying to understand.
When you said "why not go 5.3 or 4.8 instead of 370" and I agreed it would be good, it was using the assumption that the turbocharger was a constant and we were at the turbine limit already. If you can run a larger turbo(s) to match the larger engine, of course that would have a higher airflow potential.
Jack
I was under the impression that I should have small CI, small stroke and run big boost to be efficient. That is why I chose 383 (LT1) with 10:5 cr, so I could run less boost and make the same hp as another car running smaller CI/stroke and compression. So thats why I thought a 427 or 434 would be be efficient enough with the right turbo.
Because CI and and turbine size is what's gonna make the setup efficient. Also with class limitation also playing a factor.
Yes. The turbocharger (both compressor and turbine) needs to be sized appropriately to the engine displacement.
When you said "why not go 5.3 or 4.8 instead of 370" and I agreed it would be good, it was using the assumption that the turbocharger was a constant and we were at the turbine limit already. If you can run a larger turbo(s) to match the larger engine, of course that would have a higher airflow potential.
Jack
When you said "why not go 5.3 or 4.8 instead of 370" and I agreed it would be good, it was using the assumption that the turbocharger was a constant and we were at the turbine limit already. If you can run a larger turbo(s) to match the larger engine, of course that would have a higher airflow potential.
Jack
A 408 with a 76 will not be as efficient as a 5.3 with a 76 and therefore 5.3 can run more boost and make more power
But a 408 with a appropriate sized turbo for the combo can run more boost and therefore make more power than the 5.3/76 setup
Is my thinking correct now?
Launching!
Joined: Oct 2006
Posts: 201
Likes: 0
From: Grand Rapids, MI
Okay so, size doesn't make the power, the efficiency of the combo makes the power is what I am taking from this, that seem correct?
A 408 with a 76 will not be as efficient as a 5.3 with a 76 and therefore 5.3 can run more boost and make more power
But a 408 with a appropriate sized turbo for the combo can run more boost and therefore make more power than the 5.3/76 setup
Is my thinking correct now?
A 408 with a 76 will not be as efficient as a 5.3 with a 76 and therefore 5.3 can run more boost and make more power
But a 408 with a appropriate sized turbo for the combo can run more boost and therefore make more power than the 5.3/76 setup
Is my thinking correct now?
Also, it's not about hitting a boost number. There are a ton of factors at play here. Boost is just a measure of resistance. An extremely efficient engine could make more power at a lower boost level than an inefficient engine at a higher boost. Manifold PSI can only be converted to a power number if you make a HUGE number of assumptions. Total airflow = horsepower. The engine doesnt care what manifold pressure is as long as there is sufficient total airflow.
Hope that helps a bit.
Jack
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Thats why I asked the question because so many people have different opinions. So thats why I wanted some of the heavy hitters who have large CI and small CI to give their input.
I was under the impression that I should have small CI, small stroke and run big boost to be efficient. That is why I chose 383 (LT1) with 10:5 cr, so I could run less boost and make the same hp as another car running smaller CI/stroke and compression. So thats why I thought a 427 or 434 would be be efficient enough with the right turbo.
Because CI and and turbine size is what's gonna make the setup efficient. Also with class limitation also playing a factor.
I was under the impression that I should have small CI, small stroke and run big boost to be efficient. That is why I chose 383 (LT1) with 10:5 cr, so I could run less boost and make the same hp as another car running smaller CI/stroke and compression. So thats why I thought a 427 or 434 would be be efficient enough with the right turbo.
Because CI and and turbine size is what's gonna make the setup efficient. Also with class limitation also playing a factor.
The more detailed you are, the better answer you’ll get. Come up with a list of the exact parts you plan on using as well as the class, ¼ or 1/8, weight, turbo etc… Then the “pro’s” can steer you in a direction. With all the might’s and maybe’s, I don’t see how someone can steer you in a specific direction. There is no one right answer.
The larger the stroke the more stress is applied to the rods. An over square engine will put less stress on the rotating assy at the same cylinder pressures than an under square engine. It will also do it at a higher RPM which is usually beneficial in racing. If your not making more power/RPM than your rotating assy can handle and are not limited in turbo size, bigger is better. Part failure makes this impossible after a point. Efficiency is key once that point is reached. To get the most out of a limited strength part, bigger isn’t always better. To extract the most power from a limited turbo size, bigger isn’t always better.
Problem is most people live there life on boost and power on boost.
I've tuned a ton of 5.3/6.0 turbo setup's. I don't like the smaller cubes because they are turds off boost. I would never want a supra making 1300rwhp because they are way to doggy before spool.
Main reason I say bigger cubes/less boost to make the power. I race a lot of small cube cars and they take forever to spool compared to my 427/88 setup. They launch at 25psi, I launch at 8 psi.
Just a preference.
I've tuned a ton of 5.3/6.0 turbo setup's. I don't like the smaller cubes because they are turds off boost. I would never want a supra making 1300rwhp because they are way to doggy before spool.
Main reason I say bigger cubes/less boost to make the power. I race a lot of small cube cars and they take forever to spool compared to my 427/88 setup. They launch at 25psi, I launch at 8 psi.
Just a preference.
Launching!
Joined: Oct 2006
Posts: 201
Likes: 0
From: Grand Rapids, MI
Problem is most people live there life on boost and power on boost.
I've tuned a ton of 5.3/6.0 turbo setup's. I don't like the smaller cubes because they are turds off boost. I would never want a supra making 1300rwhp because they are way to doggy before spool.
Main reason I say bigger cubes/less boost to make the power. I race a lot of small cube cars and they take forever to spool compared to my 427/88 setup. They launch at 25psi, I launch at 8 psi.
Just a preference.
I've tuned a ton of 5.3/6.0 turbo setup's. I don't like the smaller cubes because they are turds off boost. I would never want a supra making 1300rwhp because they are way to doggy before spool.
Main reason I say bigger cubes/less boost to make the power. I race a lot of small cube cars and they take forever to spool compared to my 427/88 setup. They launch at 25psi, I launch at 8 psi.
Just a preference.
Jack
Seems like a lot of topics flying around since the question was vague to start with. So far I’ve heard… OEM Iron block, 8 sec ET, 1500whp, LSX block, 7 sec ET, 360-427 cu inches, might do this, might do that…
The more detailed you are, the better answer you’ll get. Come up with a list of the exact parts you plan on using as well as the class, ¼ or 1/8, weight, turbo etc… Then the “pro’s” can steer you in a direction. With all the might’s and maybe’s, I don’t see how someone can steer you in a specific direction. There is no one right answer.
The more detailed you are, the better answer you’ll get. Come up with a list of the exact parts you plan on using as well as the class, ¼ or 1/8, weight, turbo etc… Then the “pro’s” can steer you in a direction. With all the might’s and maybe’s, I don’t see how someone can steer you in a specific direction. There is no one right answer.
Of course I am not done with my current build so thats why I was asking for future references and "wishful thinking". So I know more detail is beneficial but having a good base on deciding on what blocks, cubes and stroke to go with is just as important. Im not a full LS guy yet (still in LT1 world) so its a lot I have to learn. Then when the build is under way, it would be a no brainer!
Problem is most people live there life on boost and power on boost.
I've tuned a ton of 5.3/6.0 turbo setup's. I don't like the smaller cubes because they are turds off boost. I would never want a supra making 1300rwhp because they are way to doggy before spool.
Main reason I say bigger cubes/less boost to make the power. I race a lot of small cube cars and they take forever to spool compared to my 427/88 setup. They launch at 25psi, I launch at 8 psi.
Just a preference.
I've tuned a ton of 5.3/6.0 turbo setup's. I don't like the smaller cubes because they are turds off boost. I would never want a supra making 1300rwhp because they are way to doggy before spool.
Main reason I say bigger cubes/less boost to make the power. I race a lot of small cube cars and they take forever to spool compared to my 427/88 setup. They launch at 25psi, I launch at 8 psi.
Just a preference.
From the comments left so far, my theory still does hold weight.
Lol. Well I threw OEM block out there because it was more cost effective for me. But seems as if 1500rwhp was really pushing the limits of the block. So thats whats was changing my mind in going to an aftermarket block.
Of course I am not done with my current build so thats why I was asking for future references and "wishful thinking". So I know more detail is beneficial but having a good base on deciding on what blocks, cubes and stroke to go with is just as important. Im not a full LS guy yet (still in LT1 world) so its a lot I have to learn. Then when the build is under way, it would be a no brainer!
Of course I am not done with my current build so thats why I was asking for future references and "wishful thinking". So I know more detail is beneficial but having a good base on deciding on what blocks, cubes and stroke to go with is just as important. Im not a full LS guy yet (still in LT1 world) so its a lot I have to learn. Then when the build is under way, it would be a no brainer!
I guess none of the, "Make it bigger guys" have any idea how to read a compressor map either or plot airflow on one!
Compressor's are capable of supplying X amount of airflow at X pressure. A given sized engine with a given induction system and camshaft will demand X amount of airflow at X amount of pressure as well.
Matching those two to intermingle as efficiently as possible will always give the best results. Not just, "making it bigger."
Last edited by Sales@Tick; Jan 2, 2015 at 12:04 PM.
Oh, Im building a weekend toy/street strip car right now. But the 1500hp car will be a pure racecar. I would like to compete in the X275 class or ultra street.
I lol'd at that one too.
I guess none of the, "Make it bigger guys" have any idea how to read a compressor map either or plot airflow on one!
Compressor's are capable of supplying X amount of airflow at X pressure. A given sized engine with a given induction system and camshaft will demand X amount of airflow at X amount of pressure as well.
Matching those two to intermingle as efficiently as possible will always give the best results. Not just, "making it bigger."
I guess none of the, "Make it bigger guys" have any idea how to read a compressor map either or plot airflow on one!
Compressor's are capable of supplying X amount of airflow at X pressure. A given sized engine with a given induction system and camshaft will demand X amount of airflow at X amount of pressure as well.
Matching those two to intermingle as efficiently as possible will always give the best results. Not just, "making it bigger."
